Extra parameters when interface is named vlanX

When you have a vlan with id `5` on top of a device `bond0`, you may call the vlan
interface either `bond0.5` or simply `vlan5`. The latter case is now
supported via this PR, which adds the following paramters:

```bash
VLAN_NAME_TYPE=VLAN_PLUS_VID_NO_PAD
PHYSDEV=bond0 # whatever the `attached_to` is
```

You interface identifier should be `vlan5` in this example.

For more information:
https://www.tummy.com/blogs/2006/11/30/configuring-vlans-under-fedorarhelcentos/